An orderly evening crumbled around Danny Duffy in Wednesday’s sixth inning, and he found himself swept away by the onrushing debris. The sequence cost the Royals a game in a 5-2 defeat to the Colorado Rockies, reminded of Duffy’s ongoing maturation, and displayed the consequences of rickety defense thanks to an explosive conclusion.

The unraveling began with an innocuous, two-out ground ball to the left side of the infield. Protecting a one-run lead, Christian Colon settled behind it and threw a low peg across the diamond. The throw beat Colorado third baseman Nolan Arenado. But it skimmed out of Billy Butler’s glove.

The scorer charged Colon with an error. He replaced Mike Moustakas, the team’s regular third baseman, in the field on Wednesday. Butler has replaced Gold Glover Eric Hosmer as Hosmer recovers from a broken hand.

A lone runner was aboard. From here, Duffy, 8-11, lost the plot. His offense was absent save for a solo homer by Alex Gordon and a double by Josh Willingham. The group hit into four double plays. After the fourth inning, they could not advance a runner past first base.

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Yet still they led. The Royals required Duffy to hold the line. He would strike out six batters across seven innings, but during the critical moments of this night his command evaporated.

The next batter, Wilin Rosario, hacked an inside fastball up the middle for a single. Facing a left-handed batter, Corey Dickerson, Duffy missed with two curveballs and failed to hit the zone with two subsequent fastballs. All of a sudden, the bases were loaded.

They would empty soon enough. Duffy split the plate with a 95-mph fastball to Colorado first baseman Matt McBride. Gordon tracked the blast in left, and slowed as it cleared the wall. The grand slam sank the Royals’ hopes and ended a stunning streak: By splitting this two-game set, the club failed to win a series for the first time in nine tries.

This road swing offered a chance for the Royals to rough up losing clubs like the Twins, Rockies and Rangers. Kansas City captured four of the first six games on the trip. Still, with Detroit leveling out after an early-month malaise, general manager Dayton Moore saw little reason to gloat.

“The truth of the matter is, we haven’t accomplished anything,” Moore said in a telephone conversation before the game. “We’ve got a lot of work to do. A lot of baseball to be played. Everybody has a very small window of opportunity. It’s important you take advantage of the opportunities you’re given.”

Sometimes the obstacles ahead can be self-inflicted. The Royals scratched two-time All-Star catcher Salvador Perez about an hour before Wednesday’s game. On Monday, Perez tweaked the patella in his right knee. He left the game early, and his replacement, Erik Kratz, swatted two homers. Yet there was Perez back behind the plate the next night.

Manager Ned Yost and Perez both downplayed the severity of the injury from the start. Perez insisted he felt “good” on Tuesday. A team official dubbed Perez’s departure from the lineup the next night as a “precautionary measure.”

As Perez sat out, Duffy paired with Kratz for the first time. In his last outing, on Thursday in Minnesota, Duffy lacked access to his upper-register fastball and could not complete six innings.

His velocity was not an issue against the Rockies. Duffy flung 97-mph gas in the first inning. He yielded only two singles in the first three innings.

He also inherited an early lead. Gordon demolished the first pitch of the second inning. His 14th homer of the season crashed into the second-deck seats in right.

The Royals tacked on a second run in the fourth. Willingham slapped a double past third baseman Nolan Arenado. He advanced the final two stations thanks to two fly-outs. Kratz received credit for the RBI. Willingham scored on his lineout to right.

Arenado cut the deficit in half in the bottom of the inning. He ripped a 92-mph fastball into the gap between Gordon and Lorenzo Cain. The baseball rattled around the outfield wall. Arenado landed at first and scored soon after on a sacrifice fly.

After Willingham’s fourth-inning knock, the Royals’ offense went aground. A batter did not reach again until the seventh. Gordon opened the seventh with a walk but was promptly erased when Kratz grounded into a double play.

The loss cut Kansas City’s lead in the American League Central to one game. The second-place Detroit Tigers beat the Tampa Bay Rays 6-0 earlier Wednesday.